Lecture 2 Big Bang Time Line The Birth of the Quantum Max Planck –The energy contained in radiation is related to the frequency of the radiation by the.

Similar presentations

Presentation on theme: "Lecture 2 Big Bang Time Line The Birth of the Quantum Max Planck –The energy contained in radiation is related to the frequency of the radiation by the."— Presentation transcript:

3
The Birth of the Quantum Max Planck –The energy contained in radiation is related to the frequency of the radiation by the relationship n is a positive integer called the quantum number f is the frequency of the oscillation –A discreet packet of energy, later to become known as “a photon”

4
Implications of Planck’s Law The energy levels of the molecules must be discreet Only transitions by an amount E=hf are allowed The implication is that light is discreet or quantised These quantum levels are known as number states 4321043210 4hf 3hf 2hf 1hf 0 energy n

7
Spectral Analysis of the Elements Continuous Spectrum: a collection all possible wavelengths/ frequencies of light Studying the light emitted by an object in order to know something about that object!

8
Emission Spectra Pattern of bright spectral lines produced by an element.

9
Absorption Spectra Pattern of dark spectral lines where light within a number of narrow frequency ranges has been removed.

11
Kirchoff’s Laws 1st law1st law: A luminous solid or liquid, or a sufficiently dense gas, emits light of all wavelengths and produces a continuous spectrum of radiation. 2nd law2nd law: A low-density hot gas emits light whose spectrum consists of a series of bright emission lines which are characteristic of the chemical composition of the gas. 3rd law3rd law: A cool thin gas absorbs certain wavelengths from a continuous spectrum, leaving dark absorption lines in their place superimposed on the continuous spectrum.

15
Hubble’s Discovery of the Expanding Universe (1929) Spiral nebulae known to have redshifted spectra Hubble and Humason carry out quantitative study Hubble shows velocity of recession is proportional to distance

20
Stellar Parallax ParallaxParallax is the annual shift in a star’s apparent position in the sky due to the Earth’s orbital motion. The parallax angle is half the annual shift. The parallax angle of the nearest star, Proxima Centauri, is 0.77 arcseconds.

25
The Expansion of the Universe: One should consider the galaxies located on the surface of the sphere which expands with time. As the sphere expands all lengths, including that of light increase. That means all the photons redshift. The redshift increase with the distance. The Expansion of the Universe

28
Cosmology Hubble Time The age of the universe if the expansion has been constant. t = 1/H o = ? The expanding universe probably originated in an explosion called the Big Bang between 12 and 18 billion years ago.